This invention relates generally to the method and apparatus for assembling spiral wound gasket rings within gauge rings.
A spiral wound gasket or gasket ring consists of alternate layers of spirally wound metal strip and asbestos or other suitable sealing material. Three or four loose turns or wraps of the metal strip alone without the sealing material are usually provided at the outer periphery of the gasket ring and these turns are spot welded along the outer periphery to hold the metal strip in wound relation. The gasket ring which is of a thickness greater than the metal ring is then inserted within an outer metal gauge ring with the metal ring retaining the gasket ring in retained position, but not so tight that the gasket cannot be rotated relative to the metal gauge ring.
The metal strip forming the gasket ring has a radially extending bead or ridge projecting outwardly from its outer periphery and the outer metal gauge ring has an annual groove or indentation along its inner periphery adapted to receive the radially extending bead thereby to hold the gasket ring in assembled position.
Heretofore, the outer metal ring and inner gasket ring have been assembled by various methods utilizing associated apparatus for carrying out the several methods. As an example of one type of method and apparatus, reference is made to U.S. Pat. No. 4,203,191 issued May 20, 1980 to Vernon W. Gibson, Sr., in which a method and apparatus are shown for providing inwardly directed radial forces along the outer periphery of a spiral wound gasket causing the gasket to decrease in diameter sufficiently to slip into a corresponding annular groove in a metal gauge ring. The gasket is pushed downwardly through a frusto-conical or tapered opening to decrease the diameter of the gasket and into the center of a gauge ring held in fixed position below the gasket. Upon a release of the mandrel which applies the radial forces the gasket expands outwardly into a relatively tight fit within the groove of the metal gauge ring.
Another example of prior art is shown in U.S. Pat. No. 4,019,244 issued Feb. 17, 1976 to A. B. Owen, et al, in which a spiral wound gasket assembly is formed by positioning the gasket having a bead along its outer periphery formed adjacent a groove of an outer metal ring. Dies having metal working portions are employed to form deformations or circumferential indentations in the gauge ring at selected points along the circumference of the groove to deform the groove and tighten the gasket ring therein. The amount of deformation or indentation of the groove in the gauge ring varies in accordance with the desired tightness of the gasket ring in the groove.
It is clear from the foregoing that it is difficult to obtain a uniform fit between the gasket and the outer ring. The crimping or cold flowing of metal into a void space by metal working only at spaced selected areas is normally not uniform, particularly with the outer periphery of the gasket or gasket ring being subject to variations in size. Further any deformation of the gasket could result under some circumstances in permanent deformation, and the outward expansion after such deformation might not be sufficient to perform the fit desired in the after gauge ring. Also, since the sealing is obtained by the gasket, no deformation of the gasket after the gasket is spirally wound is desired so as not to affect the sealing characteristic in any manner.